Ballance
 

Does anybody know the reciprocating to rotational ratio that was used for the balance of a speed 61? I'm guessing somewhere between 50 to 60%.
I know it's a deep question, but I thought I would give it a shot.

Thank You

Not familiar with that ratio... All I know is that usually the balance weight is calculated to balance out the weight of the piston and 2/3rd the weight of the rod (2/3rd of the rod is considered reciprocating mass, the last third is considered rotational mass.

But that is from long ago in school, and a general rule of thumb.